This is killing me. I done a substantial amount of searching, however I
haven't found what I need. Problem is as follows:

When booting the netboot image for any of Woody, Sarge or Sid, the Indy
stops taking input over the serial console as soon as the image loads.
Hitting return during the boot sequence doesn't insert blank lines, and
once the installer starts I can't send any kind of input to it. It's an
Indy 133MHz R4600, 64MB RAM, unknown SCSI HDD. Further information
available upon request, just tell me how to get it. No usable OS on the
Indy, no monitors available (yet), only serial access.

That's either a broken cable, or, more likely, a misconfigured terminal
program. 9600 8N1 on both sides should work fine.
(I use "screen /dev/ttyS1" as terminal emulator, other people like
minicom or cu better. Judging from hearsay, minicom might be a bit
less reliable.)

You know, I've been using minicom (happily) to administer my cisco
devices, but that's scary. "screen /dev/ttyS0" works like a charm. Since
I use screen for everything else I do, I don't know why I didn't try
that earlier. Thanks, Thiemo!